Ok, I have done that, but am running low on parts, so
R9 is 5.6k rather than your suggested 10k
c1 is 2.2nF rather than your suggested 1nF. The first diagram shows the circuit as it stands:
This exhibits the same problem as previously, where the power to the counter is disrupted when the solenoid is on. I don't think it is a problem to do with the 555 section, because it occurs even when that whole section is disconnected and unpowered. I can prompt the behaviour by shorting the solenoid to ground, energising it. As long as it's shorted, the counter races.
(the clock in to the counter) and
the supply voltage to the counter.
I've tried another circuit:
that is just the above circuit but with a set of batteries (common ground) for the powering the solenoid. That works fine, every time, without affecting the power to the counter: Rejoicing etc.
Ok, so my problem is decoupling the solenoid power supply from the counter supply, I think? At the moment, I have two 10uF electrolytic in parallel between the +v and ground, which is far from the 47uF that was specified on my diagram for the 555 portion (at
**broken link removed**) because I didn't have any more bigger capacitors spare.
Is it worth me beefing that up? Even running with three 10uF in parallel doesn't seem to make any difference to the shapes of the supply graph or the clock graph. Does it matter that they are polarised electrolytic caps? I have also tried adding a 10uF in parallel with the 0.1uF cap on the supply to the counter, without being able to detect any difference in voltage.
Thank you all for your time helping me with this, I really appreciate it!